The existing ultrasonic therapy system combines an imaging device with an ultrasonic therapy device, thereby a whole diagnosis and treatment plan with higher quality and higher efficiency can be provided to the patients.
Because an MRI apparatus can provide safe, fast and accurate imaging, as an imaging device to guide an ultrasonic therapy device, the MRI apparatus has been applied more widely in clinical diagnosis. However, the driving motors in the ultrasonic therapy device and the high-frequency generators in the ultrasonic therapy applicator as main electromagnetic interference sources may cause great electromagnetic interference to the imaging of MRI apparatus.
In ultrasonic therapy device, the movement positioning unit of the ultrasonic therapy applicator includes multiple driving motors to drive the focal point of the ultrasonic therapy applicator to move in three-dimensions.
As shown in FIG. 1, the motor for treatment bed 4 drives the treatment bed (not illustrated in FIG. 1) and the focal point moving board 14. It drives the treatment bed to go into or withdraw from the bore of the MRI apparatus. Focal point moving board 14 carries X, Y and Z-boards and the X, Y and Z-driving motors to approach or keep away from MRI apparatus.
The Z-driving motor 3 for Z-board is fixed on focal point moving board 14. Z-board 13 is mounted on focal point moving board 14 and it can move in Z-direction relatively.
The Y-driving motor 2 for Y-board is fixed on Z-board 13. Y-board 12 is mounted on Z-board 13 and it can move in Y-direction relatively to Z-board 13.
The X-driving motor 1 for X-board is fixed on Y-board 12. X-board 11 is mounted on Y-board 12 and it can move in X-direction relatively to Y-board 12.
The ultrasonic therapy applicator 5 is connected to X-board 11 and moves with X-board.
The Z-driving motor 3 drives Z-board 13 to move in Z-direction through Z-gearing unit (not illustrated in FIG. 1). Z-board drives Y-board 12, Y-driving motor 2, X-board 11, X-driving motor 1 and ultrasonic therapy applicator 5 to move in Z-direction. The Y-driving motor drives Y-board to move in Y-direction through Y-gearing unit (not illustrated in FIG. 1). Y-board drives X-driving motor 1, X-board 11 and ultrasonic therapy applicator 5 to move in Y-direction. The X-driving motor 1 drives X-board 11 to move in X-direction through X-gearing unit (not illustrated in FIG. 1). X-board drives ultrasonic therapy applicator 5 to move in X-direction.
This shows that the driving motors for X, Y and Z-boards will move correspondingly during the movement of the focal point of the ultrasonic therapy applicator 5. Because these motors are close to MRI imaging zone, the electromagnetic interference occurred when these driving motors work and the ferromagnetic substances contained in the motors when these motors are moving will cause great interference to the MRI imaging.
During diagnosis and treatment, the electric control unit and the high-frequency generator for supplying power to ultrasonic therapy applicator 5 of the ultrasonic therapy system will bring great interference to MRI imaging.
During MRI imaging, the factors of electromagnetic interference as above mentioned will seriously influence the accuracy of MRI imaging. Therefore, the effects of diagnosis and treatment will be influenced.
So, for an imaging device, especially for an MRI-guided ultrasonic therapy system, to reduce the electromagnetic interference is critical to the whole therapy system.